1. Field of the Invention
The present invention relates to a novel polypeptide which induces pollenosis and to a process to produce the same, as well as to a desensitization agent for treating, preventing and/or diagnosing pollenosis.
2. Description of the Prior Art
For ten and several years, the number of patients, who complain about rhinitis and conjunctivitis due to pollenosis, has been increasing in Japan in early spring. Pollenosis frequently receives much publicity from the press because the number is significantly increasing and because it occurs in early spring at which a variety of events, festivals and the like are successively held. Therefore, pollenosis has become one of the problems of the public health which could not be ignored.
It is said that pollenosis is a sort of allergies which is mainly induced by an allergen present in cedar pollens (the wording "cedar" as referred to in the invention means Cryptomeria japonica and plants of the genus Cedrus), i.e., a cedar pollen allergen. The invasion of such an allergen, dispersed in the air, into the body resulted in the formation of immunoglobulin E antibody specific to the allergen. When the body being in such conditions is re-invaded by a cedar pollen, both a cedar pollen allergen present in the invaded pollen and the already formed immunoglobulin E antibody induce an immunoreaction to cause an allergic symptom.
Until now, it is known that at least 2 different types of allergens with different antigenicities are contained in cedar pollens. The one is an allergen, which is now called "Cry j I", as reported by Yasueda at al. in Journal of Allergy and Clinical Immunology, Vol.71, No.1, Part 1, pp.77-86 (1983), and the other is an allergen, which is now called "Cry j II", as reported by Taniai et al. in FEBS LETTERS, Vol.239, No.2, pp.329-332 (1988) or reported by M. SAKAGUCHI et al. in Allergy, No.45, pp.309-312 (1990). Usually, cedar pollens contain Cry j I and Cry j II in a weight ratio of about 50:1 to 5:1, and most of the sera collected from patients with pollinosis react with both Cry j I and Cry j II. Sawatani et al. reported in Japanese Journal of Allergology, Vol.42, No.6, pp.738-747 (1993) that Cry j II exerts the same level of antigenicity as that exerted by Cry j I when assayed on intradermal test (IT) and radioallergosorbent test (RAST).
As described above, several cedar pollen allergens have been isolated and revealed for their properties and characteristics to some extent, and because of this there appears some possibilities to treat and/or prevent pollenosis by administering a purified preparation of a cedar pollen allergen to a human for desensitization. Recently, desensitization agents for such a purpose have proposed: For example, Japanese Patent Laid-Open Nos.156,926/89 and 93,730/91 propose a method to administer to human a conjugate as desensitization agent prepared by covalently binding pullulan as a polysaccharide with an allergen having a partial amino acid sequence of Asp-Asn-Pro-Ile-Asp-Ser-or Ala-Ile-Asn-Ile-Phe-Asn- at the N-terminal. Since pollenosis-inducing allergens are not restricted to Cry j I and Cry j II, other pollenosis-related allergens should be urgently isolated and their properties and characteristics revealed to establish an accurate diagnosis and an effective desensitization therapy of pollenosis.